1. Field of the Invention
The present invention generally relates to a hand held medical device. More particularly, the present invention relates to a laryngoscope, and still more particularly to a laryngoscope that is constructed of materials having relatively low magnetic susceptibilities. This provides the laryngoscope of the present invention as a useful instrument in the vicinity of a magnetic resonance scanner.
2. Prior Art
Laryngoscopes generally comprise a detachable blade and a cooperating handle which are connected together in an L-shaped configuration. The handle serves as an enclosure for one or more batteries which energize a light source in the handle. The switch for energizing the light source is usually positioned at the top of the handle immediately adjacent to the light source and is activated by the blade when it is connected to the handle and moved into an operative position. Light from the light source is directed to the light conductor disposed in or on the blade. Light passes through the light conductor to the distal end thereof to illuminate the field of view such as a patient""s mouth and larynx during the examination thereof by medical personnel and during the insertion of an endotracheal tube into the trachea of the lungs to administer anesthetic gases therein.
The prior art is replete with various types of metallic laryngoscopes, some of which are capable of illumination. Additionally, U.S. Pat. No. 4,607,623 to Bauman describes a laryngoscope constructed of non-ferrous materials such as ABS with the electrically conductive portions provided by first applying a thin copper layer to the ABS followed by electroless plating and then electrolytically plating another copper layer to form a conductive layer about 0.5 to 2 mils thick. A thin layer of aluminum is subsequentially applied to the copper coating in those areas intended to be reflective. The batteries powering this device are not further described, but may be of a nickel/cadmium type commonly used for such application. Nickel/cadmium batteries are not considered to be relatively nonmagnetic and would not be useful with the laryngoscope of the present invention.
U.S. Pat. Nos. 310,004 to Weston; 485,089 to Carhart; 2,282,979 to Murphy; 3,352,715 to Zaromb; 3,673,000 to Ruetschi and 4,318,967 to Ruetschi disclose anti- or non-magnetic materials in cells or batteries. Additionally, U.S. Pat. Nos. 2,864,880 to Kaye; 2,982,807 to Dassow et al.; 4,053,687 to Coiboin et al.; 4,264,688 to Catanzarite; 4,595,641 to Giutino; 5,104,752 to Baughman et al.; 5,149,598 to Sunshine; 5,173,371 to Huhndorff et al.; 5,194,340 Kasako; 5,418,087 to Klein; and 5,443,924 to Spellman relate to batteries having means for assuring that proper battery polarity is established. However, none of these patents describe power sources that are useful with the hand held medical device of the present invention because they either include at least some magnetic components, do not have sufficient energy density for extended use or do not have a terminal configuration similar to that of the present invention. U.S. Pat. No. 4,613,926 to Heitman et al. discloses an illuminating assembly for an MRI scanner.
There is needed a lighted laryngoscope that is predominantly constructed of metal so that the instrument is capable of withstanding the abusive treatment conditions which surgical instruments are sometimes subjected to. For this purpose, the laryngoscope of the present invention is constructed largely of metal components. However, with ever increasing use of magnetic resonance scanning to aid medical personnel during pre- and post-clinical and surgical procedures, the metal components must be constructed of materials that have as low a magnetic susceptibility as possible.
The laryngoscope of the present invention is constructed of materials including metal components having very low magnetic susceptibilities. Those parts not made of metal are preferably formed of a thermoplastic material, for example an acetal compound such as DELRIN. The battery powering the laryngoscope lamp is also constructed of materials having low magnetic susceptibility. Lithium batteries are preferred, and all components such as the casing, terminal leads, current collectors and collector leads, some of which are typically made of nickel, are constructed of stainless steel nonmagnetic austenitic. The battery further includes a unique terminal configuration that prevents the inadvertent use of other batteries, including non-magnetic batteries, in the laryngoscope. A unique lamp retaining mechanism provides for quick and easy replacement of the lamp.
These and other aspects of the present invention will become more apparent to those skilled in the art by reference to the following description and to the appended drawings.